| dc.description.abstract | Pulse coding and pulse compression techniques have been used extensively in radar, sonar, non-destructive testing and seismic imaging1-4. Its application in medical
imaging has been sparse and few5-8. Possible reasons could be, (i) limitations on time-bandwidth product5,7 due to transducers operating in 1 to 10 MHz range with only 60%
fractional bandwidth, (ii) frequency dependent attenuation in soft tissues and (iii) a need to keep the sidelobe levels that result from pulse compression processing below certain
levels7, for improved contrast resolution. With significant improvements in processing hardware and software, real time implementation does not appear to be a significant
problem7'10. In this paper we have examined two possible applications of pulse coding techniques. The possibility of increasing the effective bandwidth of a transducer (and hence the time-bandwidth product) through pre-enhancement of the drive signal has been evaluated with simulation studies. The increasing penalty on the sidelobe levels is also examined. As a second application, the flexibility to change the center frequency fo and bandwidth (delta)f of the coded signal has been exploited to study experimentally the sub-resolution scattering microstructure of a scattering object. | en_US |
